The present invention relates to a developing replenisher material for use in a image forming device, e.g., electrostatic copying machine.
1. Discussion of the Background
In some electrophotographic copying machines, a photosensitive drum is held in contact with a liquid developer comprising a toner carrier liquid with toner particles dispersed therein thereby to cause the toner particles to be electrostatically attracted to an electrostatic latent image on the photosensitive drum to develop the latent image into a visible image.
The liquid developer is supplied onto the photosensitive drum from a developer tank through a supply nozzle of an image developing container. As toner particles in the liquid developer are consumed by being electrostatically attracted to the latent image on the photosensitive drum, the amount of toner particles in the developer tank is reduced, and the developer tank is replenished with new toner particles from a toner replenishing device to make up for the consumed toner particles.
The toner particles are replenished in the form of ink-type replenisher toner containing toner particles and a toner carrier liquid which are mixed at a ratio of 11:89, for example. The toner particles in the replenisher toner as they are mixed into the liquid developer stabilize the density of the liquid developer.
When many copies are successively produced or an original with a solid image at a large image area ratio is copied, the amount of consumed toner particles is increased. Therefore, an increased amount of replenisher toner should be added to compensate for the toner particle shortage for stabilizing the density of the liquid developer. Since the proportion of the toner carrier liquid is much larger than that of the toner particles in the replenisher toner, as described above, the total amount of toner carrier liquid in the liquid developer is increased of necessity as the replenisher toner is added to the liquid developer. Continued supply of a toner carrier liquid to the developer tank thus results in an overflow of the toner carrier liquid from the developer tank.
One solution to prevent such an overflow has been to provide a sensor in the developer tank for detecting the level of the liquid developer to limit the amount of liquid developer that can be stored in the developer tank. More specifically, when the amount of the liquid developer in the developer tank reaches a prescribed level, the sensor is activated to stop the operation of the toner replenishing device. Where the developer tank is of a small size and hence of a small capacity, however, the sensor will shut off the toner replenishing device soon since the liquid developer will quickly arrive at the preset level as new toner is replenished, especially when a relatively large solid image is copied Consequently, it is difficult to keep the liquid developer in the developer tank at a desired mixture ratio.